Since Chevrel phase compounds have a critical temperature higher than a temperature of liquid helium and have a very high critical magnetic field, many studies have been made. Moreover, certain Chevrel phase compounds such as, for example, copper, Chevrel phase compounds, wherein the metal element can be chemically or electrochemically released from or received in the compound without destroying the skeletal structure of Mo.sub.6 S.sub.8 of the compound, have been studied for application as electrode materials of electrochemical elements. In a conventional process of manufacturing Chevrel phase compounds, it powders of various metal elements, metallic molybdenum powder and sulfur powder were mixed after milling, the mixture was placed in a quartz glass tube and sealed under reduced pressure, and sintered at 400.degree. C. for 12 hours, then at 600.degree. C. for 12 hours and finally at 1000.degree. C. for 24 hours.
In this process, the starting materials contain sulfur which is apt to react with most metals and are sintered after placing in a reaction tube and sealing the tube under reduced pressure, so that it is necessary to use as the reactor tube, a quartz glass tube which is stable against sulfur and can be worked as desired. After the sintering, it is essential to open the quartz glass reaction tube in order to withdraw the resultant product thus making it difficult to use the quartz glass reaction tube several times. In addition, if large amounts of the product are prepared in one batch, sulfur will be gasified during the course of temperature rise. When the pressure of the resultant gas becomes too high, the quartz glass reaction tube is broken. Thus, the production process is complicated and involves a problem in the industrial production of the compound.